1. Field of the Invention
This invention relates to a method for fabricating CMOS semiconductor devices and, more specifically, to a method for forming regions of opposite conductivities utilizing a single masking step, thereby resulting in fewer process steps, with a resultant decrease in device cost.
2. Description of the Prior Art
One example of a prior art process utilized to fabricate semiconductor regions of opposite conductivity types is given in U.S. Pat. No. 3,928,081 issued to Marley, et al. In the prior art fabrication of semiconductor devices requiring the formation of regions of opposite conductivity types, typically a first mask is utilized to define the regions which are to be doped to a first conductivity type and a second mask is utilized to define the regions which are to be doped to a second conductivity type opposite the first conductivity type. Thus, such prior art fabrication methods require the use of at least two masking steps in order to define and thus form regions of opposite conductivity types.